Valve Adj Virgin - Advice Needed

tumalo98199 · 09:28 PM

Hi All,
After reading my Bentley Manual, 101 Projects, Tech Articles, etc. I decided to dive into a "two man wrench" job (Wayne's Skill Rating). I'm ready to get #1 TDC but having trouble with this mystical "Z1" referenced.

I've rotated the engine with the rotor pointed towards the "notch" on the distributor. Looking down at the Crank Pulley there is NO bright shiney Z1 glaring at me. There are several small notches throughout the circumfrence of the Pulley but no noticable Z1. When I strain and look between the two pulleys I see some sort of engraving like a mirage.

Is this where I should be looking for the Z1 or should it be staring me in the face? The engraving I am looking at is slight off and left of the casing split when the rotor is TDC. Is it good enough the rotoe is pointed in at the arrow in the Distributor?

I also hesitate to think I am TDC because there is 0 (ZERO) tolerance between valve and rocker. Not even close to weasel in my feeler guage. Since previous work was done by reputable shop seems to me I would have some tolerance in there and thus doubt my work so far.

Am I over analyzing?

Thanks so much for any advice you can spare!!!!

tumalo98199 · 04-01-2006, 07:18 AM

I used the search but can't really find the answer. Just looking for advice to make 100% sure I'm at TDC since I can't locate the Z1 indicator.

89turbocabmike · 04-01-2006, 10:14 AM

An easy way to tell is to look at the rockers and see if they are on the lowest (base) part of the cam lobe. The notch in the distributor and Z1 will not necessarily match exactedly because of initial advance setting. It is more critical that Z1 and the case line are matched. Z1 will be 120 degrees between the other major timing notches on the pulley. It will usually have one or two notches 5-15 degrees to the left of it and another notch about 30-35 degrees to the right and then the forementioned notches at 120 degrees and 240 that you will be using for adjusting the other cylinders. Also sometimes you can't initially feel the play at the rocker as there can be quite a bit of stiction between the foot and valve stem.

Eagledriver · 04-01-2006, 11:16 AM

It's not critical to be at exactly Z1 ot the other 120 degree marks. If the rotor is pointing at the correct cylinder wire then you'll be close enough. The previous response from Mike should help you figure out which mark is which. You'll also feel the compression when you turn the engine and it will "drop off" as you get to TDC.

The clearance will be very small (.004 isn't very much). As long as it's got some clearance I wouldn't worry about how it was in the past. If it really is at zero or holding the valve open it can cause problems (burned valves). If the rocker can slide sideways by wiggling it then you have some clearance. I personnally like to set the clearance at .003 inches rather than trying to get .004 exactly. The tempurature you do this at will make a difference as well. If the engine is very cold (below 50 degrees or so) then You'll end up with too much clearance when it warms up. Lots of people try to set a "tight" .004 inches. This is not an accurate way to set the clearance IMO so I use .003 and try to get an exact to slightly loose fit.

Another tip: If you turn the adjuster in until you feel it bottom out and back off 36 degrees you should have .004 clearance. I try for 30 degrees and then measure to see that I have at least .003 inches.

-Andy